There have conventionally been proposed techniques for receiving, via a touch panel, a mouse, or the like, an instruction entry that designates, by means of two coordinate values (typically, x-coordinate and y-coordinate values), the position of a point within a predetermined two-dimensional region, and processing the entered coordinate values. For example, the literature identified below discloses one such technique.    Patent Literature 1: Unexamined Japanese Patent Application KOKAI Publication No. 2003-114760
[Patent Literature 1] discloses a technique for moving a mouse pointer, which enables precise moves of the pointer by controlling it to move by a travel distance per unit operation amount that is shorter than a travel distance per a unit operation amount. Meanwhile, techniques for drawing a curve of any kind on a screen by an entry of coordinate values via a touch panel or a mouse are also widely used.
It is common to draw a change in a stock price, a weight, or the like over time with a graph whose horizontal axis (X coordinate) represents a time and whose vertical axis (Y coordinate) represents a value at a time. According to line drawings, the position of a point included in a line is specified by a first coordinate value and a second coordinate value (in this example, corresponding to an X coordinate and a Y coordinate, respectively), and merely one second coordinate value Y is acquired with respect to the first coordinate value X in the form of an explicit function like y=f(x).